Brake control system



Sept. 1, 1942. 'c. M. HINES BRAKE CONTROL SYSTEM Original Filed March29, 1941 INVENTOR ,OLAUDE M. HINES ATTORNEY Patented Sept. 1 1942 BRAKECONTROL SYSTEM Claude M. Hines," Pittsburgh, Pa., assignor to TheWestinghouse Air Brake Company, Wilmerding, Pa., a corporation ofPennsylvania OriginalapplicationMarch 29, 1941, Serial No;

385,88'7.- Divided and this application June 28, 194-1, Serial No.400,157

11 Claims.

This invention relates to brake'control systems for vehicles, such asrailway cars and trains,-

which systems are of the type having means for automatically releasingthe brakes associated with the wheels in response to the slipping of thewheels to prevent the sliding thereof, the present application being adivision of my priorapplication Serial No. 385,887, filed March 29,1941,- and assigned to the assignee of the present application.

As is well known, the application of the brakes on a vehicle wheel to adegree sufficient to exceed the limit of rolling friction or adhesionbetween I the Wheel and the road surface or rail'causes the wheel todecelerate rapidly to a locked or nonrotative condition and slide.

In describing my present invention, I employ the term slide or slidingcondition to desig nate the locked or non-rotative condition of thewheel in which it is dragged along the rail. As distinct from the termslide I employ the term slip or slipping condition to designate therotation of a vehicle wheel at a speed greater or less than a rotativespeed corresponding to the speed of travel of the vehicle at a giveninstant, Whether the wheel is momentarily decelerating or accelerating.

It is desirable to prevent a vehicle wheel, particularly to a railwaycar wheel, fromsliding because the sliding of the wheel develops fiatspots on the wheel, necessitating replacement or repair of the wheels.

Various types of automatic brake control de-' vices have heretofore beendevised for the purpose of preventing the sliding of vehicle orcarwheels; One type of such automatic brake'control device comprises awheel-slip detecting device of the so-called rotary inertia type havinga fly-wheel, of relatively heavy mass,- driven 3 through a resilientconnection by a shaft that rotates in accordance with the speedofrotation of a vehicle wheel or wheel-and-axle assembly. The degree ofrotational shift of the fly-wheel with respect to the driving shaft isproportional to the rate of deceleration or acceleration of the drivingshaft. Suitable switch means is provided closed in Patent 2,198,033of C.C. Farmer. In

this patent,the rotary inertia device is contained in a casingconstituting an extensionof' the jour-' nal housing at the end of awheel axle and a suitable coupling is provided between the end of theaxle and the driving shaft of the rotary inertia device.

It has been found, however, that theshock and jar incidenttooperation-of a car along-a track causes fretting corrosion of thebearings supporting the fly-wheel on its driving shaft, which corrosioninterferes with the accuracy and sensitivity ofthe device. r

I have accordingly devised a novel device, which is fully described andclaimed'inmy parent" I application Serial No. 385,887, referred toabove; Which device isfreefrom the objectionable characteristics ofheretofore-known devices.

Briefly, this novel wheel-slip detecting device comprises a rotary diskof non-magnetic conducting material which is driven in accordance withthe'speed ofrotation of a wheel unit with respect to the wheel unitdependinguponthe direction of rotation of the wheel unit, therebyautomatically serving as a means for detect-- ing the direction ofrotation of the wheel unit. The braking effect exerted on the rotarydisk by the eddy current braking means is such that the rate of rotativedeceleration of the wheel unit begins to slip, in which case the rotarydisk is decelerated at a lesser rate than the wheel unit and thus shiftsfrom the one extremity of movement with respect to the wheel unit, inwhich it is positioned normally according to'the direction of rotationof the wheel unit, to the opposite extremity of movement thereof withrespect to the wheel unit.

It is an object of my present invention to provide suitable'apparatusadapted to function in connection with the wheel-slip detecting deviceof my parent application Serial No. 385,887 for the purpose of causingan automatic release of the brakes associated with a slipping wheel.

It is a further object of my presentinvention to provide apparatus ofthe type indicated in the foregoing object and further characterized bymeans for insuring a continued reduction in the degree of application ofthe brakes to below a' certain degree, once a wheel beginsto slip andindependently of subsequent variation in the condition of the slippingwheel, before-permitting reapplication of the brakes'on the slippingWheel,

The above objects, and other objects of my invention which will be madeapparent hereinafter, are attained in an illustrative brake controlequipment subsequently to be described and shown in the accompanyingdrawing, wherein Fig. l is a simplified diagrammatic view showing afluid pressure brake equipment for the wheels of a four-Wheel car truckand including the wheel-slip detecting device and associated controlapparatus of my invention,

Fig. 2 is an enlarged fragmental vertical sectional View takensubstantially on the line 2-2 of Fig. 1, showing details of thewheel-slip detecting device included in my invention, and

Fig. 3 is a fragmental sectional view, taken on the line 3-3 of Fig. 2,showing further details of construction.

Description Referring to Fig. 1 of the drawing, the brake controlequipment shown therein is limited to a single four-wheel car truckhaving two wheeland-axle assemblies carried in a truck frame (not shown)of conventional design. In the drawing, only one wheel H of eachwheel-andaxle assembly of the car truck is shown, it being understoodthat each of the wheels shown is fixed at one end of an axle [2, to theopposite end of which a similar wheel (not shown) is fixed.

The brakes associated with the wheels Il may be of any suitable type,such as the conventional clasp shoe type adapted to be applied andreleased through conventional brake levers and brake rigging in responseto the supply of fluid under pressure to and the release of fluid underpressure from one or more brake cylinders l3, two brake cylinders beingshown for purposes of illustration. For simplicity, the brake shoes andthe brake rigging are omitted from the drawing.

Fluid under pressure is, supplied to the brake cylinders and releasedtherefrom under the control of the operator of the car or train, by anysuitable well-known type of pneumatic brake control equipment, either ofthe automatic or straight-air type. For purposes of illustration, I haveindicated a simplified type of brake control equipment which is of thestraight-air type, but it will be understood that the particular type ofoperator-controlled equipment is immaterial for the purposes of myinvention.

As shown, the brake control equipment includes two train pipes 14 and[5, the sections of which on each car are connected through hosecouplings l6 between successive cars in conventional manner.Conventional angle cocks I! at opposite ends of the car sections oftrain pipes I4 and I5 may also be provided. The pipe I, hereinafterreferred to as the supply pipe, is constantly charged to the pressure ina reservoir l8, hereinafter referred to as the main reservoir, through abranch pipe [9.

The fluid pressure in the pipe [5, hereinafter referred to as thecontrol pipe, is varied in accordance with the desired degree of brakeapplication as by a manually operative brake valve device 2| of theself-lapping type.

The brake valve device 2| is of Well-known construction and willtherefore be only functionally described. Brake valve 2| comprises anoperating handle 22 efiective upon rotary movement in a horizontal planeto correspondingly shift a rotary operating shaft controlling theoperation of suitable supply and release valves. With the brake valvehandle 22 in its normal or brake release position, fluid under pressureis 7 released from the control pipe I5 to atmosphere by way of a branchpipe 23, connecting the control pipe to the brake valve device, and anexhaust port and pipe 24. When the brake valve handle 22 is shifted outof its brake release position into a so-called application zone, fluidunder pressure is supplied from the supply pipe l4 to the control pipe[5 by way of a branch pipe 25, connecting the supply pipe to the brakevalve device, and thence through the pipe 23 to the control pipe I5.

The character of the brake Valve 2| is such that the pressure of thefluid established in the control pipe I5 is substantially proportionalto the degree of displacement of the brake valve handle 22 out of itsbrake release position. If the pressure in the control pipe tends toreduce for some reason, such as leakage, fluid under pressure isautomatically supplied to maintain the pressure therein at a valuecorresponding to the position of the brake valve handle. Thispressure-maintaining feature will be referred to hereinafter.

The branch pipes 23 and 25 connecting the control pipe I5 and supplypipe l4 to the brake valve device 2| have suitable manually controlledvalves 26 therein. These valves may be of any suitable type and arenormally in open position when it is desired to control the pressure inthe control pipe l5 by means of the brake valve device 2l shown. If itis desired to control the pressure in the control pipe [5 by means of abrake valve device, similar to the brake valve 2| located on another carin a train, the valves 26 may be operated to closed position thuscutting the brake valve device 2| shown in Fig. 1 out of operation.

The brake control equipment further comprises a super-sensitivehigh-capacity relay valve device 21, preferably of the type describedand claimed in Patent No. 2,096,491 of E. E. Hewitt, and a magnet valvedevice 28 for controlling communication through a branch pipe 29connecting the control pipe l5 and the control chamber of the relayvalve device 21.

Since reference may be had to the above-mentioned patent for details ofconstruction and operation of the relay valve device 21, the relay valvedevice will be only functionally described herein.

The pressure of the fluid supplied from the control pipe [5 through thebranch pipe 29 to the control chamber of the relay valve device 21 iseffective to operate the relay valve to supply fluid at a correspondingpressure, or any desired ratio of pressure to that established in thecontrol ,pipe, to the brake cylinders l3 through a brake cylinder pipe3| from a branch pip 32 of the supply pipe M. It will be understood thatthe relay valve device 21 is of the self-lapping type so that the supplyof fluid under pressure to the brake cylinders is automatically lappedor out-off when the pressure in the brake cylinders corresponds to, oris a selected ratio to, the pressure in the control pipe I5 and suppliedto the control chamber of relay valve device 21,

A pressure-responsive switch device 34, preferlably of the type shown inPatent 2,095,492 to E. E. Hewitt, is connected to the brake cylinderpipe 3| by a branch pipe 35 and. is operated in response to variationsof brake cylinder pressure. As diagrammatically shown, the pressureswitch 34 comprises a movable contact element 36 having an associatedpair of fixed insulated contacts 31. Whenthe pressure in the brakecylinders l3 exceeds a certain pressure, such as five pounds per squareinch, the contact element 36 is snapped into engagement with thecontacts 31 and is maintained in engagement therewith as long as suchcertain pressure is exceeded. When the pressure in the brake cylindersI3 reduces below five pounds per square inch, the contact element 36 issnapped out of engagement with the associated pair of contacts 31.

The magnet valve device 28 is of standard construction and comprises acasing having a chamber 38 formed therein in which is contained adouble-beat valve 39, the valve 39 being biased by a coi1 spring 4| intoan upper seated position and operated against the force of the spring 4!by energization of an electromag-net or magnet winding 42 to its lowerseated position.

In its upper seated position, the double-beat valve 39 establishescommunication between the two sections of the branch pipe 29 therebypermitting fluid under pressure to be supplied from the control pipe Eto the control chamber of the relay valve device 2'3 and releasedtherefrom in accordance with the variations of pressure in thecontrolpipe l5.

In its lower seated position, the double-beat valve 39 cuts offcommunication between'the two sections of the branch pipe 29 andestablishes a communication through which the section of the branch pipe29 connected to the relay valve device Z1 is exhausted to atmospherethrough a relatively large-sized port 44, thus reducing the :pressure inthe control chamber of the relay valve device 2'! independently of thepressure in the control pipe [5.

As will be explained in greater detail hereinafter, the magnet winding42 of the-magnet valve device 2-8 is normally deenergized, therebypermitting the control of the brakes by the operator through .variationsof the pressure in the control pipe I5. Energization of the magnetwinding 42 of the magnet valve 28 to effect release of the brakesindependently of the pressure in'the control pipe is eiiected byapparatus including =one or more wheel-slip detecting devices 45,constructed and operatingaccording to my invention, and'a pair of relays46 and.

Referring to Figs. 2 and 3, a wheel-slip detecting device 45 isassociated with each wheeland-ax-l'e assembly of a car truck. Eachdevice 45 comprises a casing 58 which is attached, as by a plurality ofscrews or bolts 49, to the open end of the axle journal 55 in place ofthe usual end cover. In this connection it should be understood thatWhile I have shown a particular manner of installation of the Wheel-slipdetecting devices 45 at the end of an axle journal, lany other suitablemanner of mounting these devices may be employed.

In order to separate the working parts of the wheel-slip detectingdevices from the interior of the axle journal in a maner to preventpossible entrance of oil, grease, dirt or other foreign particles whichmight interfere with the proper operation of the devices, a suitableguard may be provided, which may take the form of an annular member 5iof rigid construction having a suitable annular sealing ring 52 of :feltor rubber or other suitable material for engaging the outer surface ofthe axle l2, the member 5| being secured in position between the casing'48 and the end of the axlejournal 59.

On the outside central portion of the :casing 18 is a protruding boss 54having'a recess on the interior thereof for receiving a spindle or studbolt 53, the outer threaded end of which extends through an opening inthe boss and is provided .with a suitable lock washer 55 and nut 56 {forsecuring the spindle to the casing. The location of the boss 54 is suchthat the spindle 56 .is in coaxial alignment with the axle l2.

Rotatably mounted on the spindle 53, as by ball-bearings 51 at oppositeends thereof, is a tubular member or sleeve 58 having secured on theoutside thereof a sleeve 59 of insulating material in which aredisposedin side-by-side spaced relation three collector rings 6|, 62 and63.

Secured to the tubular member 58 at the inner end thereof adjacent theouter end of the axle 1-2 is a relatively thin disk 65 of non-magneticsheet material, such as brass or aluminum. The tubular member 58 isthreaded at the inner end thereof and a nut "66 is screwed thereon tosecurethe disk 65 to the tubular member .58.

contact fingers i l and 12, which contactfingers are connected byconnectors 35 and 82, respectively, that are embedded Within theinsulating sleeve, to the collector rings 6i and 62 respectively.

The disk '65 carries, in insulated relation thereto, -a contact member13 of conducting material. The contact member 13 has projections formedat the opposite ends thereof which Willhereinafter be referred to ascontacts 74 and 5.5.

Thecontact member 73 is connected by aiflexible wire H to a comiector orterminal .post 18 secured in the insulating sleeve 59 and connectedby aconnector "E9, embedded in the sleeve, to

the collector ring 63.

Associated respectively with each of the collector rings BI, 62 and 63are brush devices 6m,

in insulated relation to the casing 48, each brush secured to the casing48 by insulated bolts which 'form the terminal or binding posts for theconnection of wires to'the brush devices.

Associated with the disk 65 is a permanent magnet 89 of substantiallyU-shape, the magnet being suitably mounted in magnetically insulatedrelation to the casing 48, as by a rib 6! of the casing, in straddlingrelation to the peripheral portion of the disk.

Upon rotation of the disk between the legs of the permanent magnet 89,eddy currents are produced in the disk which, in familiar manner,

set up a magnetic -flux reacting with the magnetic fluxof the permanentmagnet in a manner 'to produce a drag or a retarding effect resistingrotation of the disk.

The retarding efiect, resisting rotation of the disk 65, exerted by themagnet 83 varies with the speed of rotation of the disk due to the-factthat the kineticenergy-in the disk increases as the square oftherotational velocity whereas the dragor actual retarding force exertedmagneticallyon-the disk increases only in direct proportion to therotational velocity of the disk. This variable rate of retardation ofthe disk will be referred to hereinafter and explained in greaterdetail.

As will be seen in Fig. 2, the driving pin 59 extends through thearcuate slot 68 in the disk 65 and between the parallel-extendingcontact fingers H and 12, the position of the arcuate slot 68 withrespect to the contact fingers H and 12 being such that due to the dragon the disk 65 produced by magnet 89, the pin 69 engages one or theother of the contact fingers H or 12, depending upon the direction ofrotation of the axle I2 and shifts the contact fingers into contact withthe associated contact 14 or 15. Thus, assuming that the axle l2 rotatesin a clockwise direction in Fig. 3, the pin 69 engages the contactfinger H and bends it into contact with the contact 14. If the axle [2were rotating in a counterclockwise direction, the pin 69 would shift tothe opposite extremity of the arcuate slot 68, engage the contact finger12 and bend it into contact with the contact 15. In other words, contactfingers 'II and 12 are tensioned so as to disengage the associatedcontacts 14 and and do not engage the contacts 14 and 15 unless the pin69 is shifted to the corresponding extremity of the arcuate slot 68 indisk 65.

The magnet 89 is so designed as to produce a rate of retardation of thedisk 65 which exceeds that of the axle as long as the wheels fixed onthe axle do not slip. The rate of rotative deceleration of the wheelsfixed on the axle I2 does not exceed a rate corresponding to a rate ofretardation of the car or train of four or five miles per hour persecond as long as the wheels do not slip. If the wheels slip, however,the wheels will attain rates of rotative deceleration greatly in excessof five miles per hour per second, attaining rates corresponding to arate of retardation of a car or train as high as thirty or forty milesper hour per second. In any case, whenever slipping of the wheelsoccurs, a rate of rotative deceleration thereof corresponding to aretardation rate of the train of at least ten miles per hour per secondis established so that rotative deceleration of the wheels at such rateis a positive indication of a slipping condition thereof.

The magnet 89 is so designed with respect to the disk 65, therefore,that it produces a rate of rotative deceleration of the disk, assumingrotation of the disk independently of the axle, at a rate exceeding tenmiles per hour per second.

Thus, as long as the wheels do not slip, the magnet 89 causes the disk65 to be rotatively decelerated more rapidl than the axle l2 andconsequently disengagement of the contact finger II (or 12) from itsassociated contact 14 (or 75) does not occur.

If the wheels slip, however, the axle rotatively decelerates at agreater rate than the disk 65. Consequently the pin 69 shifts from theone extremity of the arcuate slot 68 to the opposite extremity andmomentarily engages the contact finger H or 12 adjacent that end of theslot and shifts it into contact with the associated contact 14 or 15.Thus, as seen in Fig. 3, if the wheels slip, the pin 69 will shift inthe left-hand direction from the right-hand extremity of the slot 68 tothe left-hand extremity of the slot to engage the contact finger 12 andbend it into engagement with the contact 15.

As previously mentioned, the rate of deceleration produced by the magnet89 on the disk 65, assuming free rotation of the disk 65 indepententlyof the axle l2, varies with the speed of rotation of the disk. Thereason for such variation is that the retarding force produced on thedisk by the magnet 89 increases directly in proportion to the rotationalspeed of the disk whereas the kinetic energy or momentum in the diskincreases with the square of the rotative Velocity of the disk. It willthus be seen that at the instant a wheel begins to slip, the rotativeretardation rate of the disk 65 will be higher at the lower speeds thanat the higher speeds. This is so because the percentage of themagnetically produced braking or retarding force relative to the inertiaforce or momentum of the disk is greater 'at the lower speeds than atthe high speeds.

It may happen, therefore, that at low train speeds for example belowtwenty miles per hour, the rate of retardation on the disk 65 at theinstant wheel slip occurs may correspond to a rate of retardation of thecar of fifteen to twenty miles per hour per second whereas the rate ofretardation of the disk produced by the magnet at higher speeds, such asin excess of sixty miles per hour, may only be a rate corresponding to arate of retardation of the train of ten miles per hour per second.

Thus the wheel axle 12 will begin to shift rotatively backward withrespect to the disk 65 at different rates of rotative deceleration ofthe disk depending upon the rotative speed of a wheel at the instant itbegins to slip. In any case,

however, the slipping condition of the wheels I is practicallyinstantaneously detected.

As will be presently described, I employ the retrogressive or backwardrotative shift of the axle with respect to the disk 65 and theconsequent operation of one or the other of the contact fingers II and12 to control the relays 46 and 41 in a manner to cause energization ofthe magnet winding 42 of the magnet valve 28 so as to produce a rapidreduction of the pressure in the brake cylinders I3.

The relays 46 and 4'! are identical in construction and are of theso-called neutral type. Each of the relays 46 and 41 is of conventionalconstruction comprising a magnetic core, not shown, a pair of separatewindings designated a and b" respectively and an armature effective,when picked-up to operate a pair of front contacts c and d from theirrespective normally open positions to closed positions.

Either of the windings a. or b of each of the relays 46 and 4'! iseffective when energized to cause pick-up of the armature and closing ofthe front contacts thereof.

The arrangement of the contact fingers H and 12 of the wheel-slipdetecting device 45 associated with the left-hand wheel unit shown inFig. l is such that the contact finger 1| controls energization of theupper winding a of relay 46 Whereas the contact finger 12 controlsenergization of the upper winding a of the relay 61.

The arrangement of the contact fingers 'H and 12 of the wheel-slipdetecting device 45 associated with the right-hand wheel unit shown inFig. 1 is such that the contact finger H controls energization of thelower winding 1) of the relay 46, whereas the contact finger 12 controlszrliergization of the lower winding b of the relay The various circuitsfor energizing the windings of the relays 45 and 41 under the control ofthe wheel-slip detecting devices 45 will be described hereinafter indetail in connlection with an assumed operation of'the brake equipmentshown in Fig. 1'.

Operation Letitbe assumed that the car or train having the wheel truckshown in Fig.- 1 in travelingdesired degree of application of thebrakes.

The control pipe I5 is thus charged with fluid at a pressurecorresponding to the position of the brake valve handle, for examplefifty pounds per square inch.

Upon the charging of the control pipe fluid at. the pressure in thecontrol pipe flows from the control pipe through the branch pipe 29 tothe control chamber of the relay valve device 21. The relay valvedevice'zl. accordingly operates, as previously described, to supplyfluid under pressure from the supply pipe l4. and branch pipe 32 throughthe brake cylinder pipe 3| to thebrake cylinders l3, the pressureestablished in the brake. cylinder corresponding to, or having a desiredratio to, the pressure established in the control pipe l5. The brakesare accordingly applied on the two wheel units of the wheel truck shownin Fig. l to a degree corresponding to the fluid pressure established inthe brake cylinders l3.

Whenever the pressure in the brake cylinders l3 exceeds a predeterminedpressure, such as live pounds per square inch, the movable, contact 36of the pressure switch 34 is'snapped into its closed position engagingits. associated contacts 31.

The windings a and b. of the relay 46 are thus simultaneously energized.The circuit for ener-- gizing the winding a of the relay 46 extends fromthe positive terminal of a suitable source of direct. eurrent,.such as astorage battery 95 which may be the usual battery forsupplyingillumination current, by way ofa wire hereinafter referred toas the positive battery wire 96, a branch wire 9], brush device 63a ofthe wheel-slip detecting device 45 associatedwith the left-hand wheelunit, collector ring 63, connector 19, terminal post 18; wire 11,contact 14, contact finger H, connector 8|, collector ring 61, brushdevice Bla, a wire 98, winding a. of relay 4B, and a wire 99 hereinafterreferred to as the negative battery wire and including the contacts ofthe pressure switch 34', to. the negative terminal of the battery 95.

The circuit for energizing the winding b of relay 46 extends from thepositive terminal of the battery 95 through the positive battery wire96, a. branch wire I 9|, brush device 63a of the wheelslip' detectingdevice 45associated with the righthand wheel unit, and thence in amanner similar to that previously described for the left-hand wheel-slipdetector. 45 and including the contact finger H to the brush device 61a;and thereafter by way of' the wire I02 including the winding b oftherelay 46 to the negative battery wire 99.

Upon the energization of the windings a and b of the relay 45 in themanner just described, the front contacts 0 and def the relay areactuated the control of the operator.

to their respective picked-up or closed positions.

The contact 0 of the relay 4-6 is effective in its closed position toestablish a self-holding circuit for maintaining the winding a of therelay energized independently of the contact finger H of thecorresponding wheel-slip detecting device 45. This self-holding circuitextends from the positive terminal of the battery 95 by way of thepositive battery wire 95, a branch wire I94, a wire [05, contact 0 ofrelay 46, Wire 98 including the winding. aof relay 46 to the negativebattery wire 99 and thence through the contacts of pressure switch 34 tothe negative terminal of the battery 95.

It will thus be seen that when an application of the brakes is initiatedwhile the wheels are rotating in a direction to cause engagement ofthe'contact finger H with the corresponding contact l4.-of the severalwheel-slip detecting devices 45,. the contacts of the relay 46 areactuated to their respective picked-up or closed positions andmaintained in such position thereafter independently of the contactfinger H of the wheelslip detecting devices as long as the pressureswitch 34 remains. in its closed position.-

Althoughactuated to its picked-up or closed position, the front contactd of the relay 45. is ineffective to produce an immediate result as willbe made clear hereinafter.

Assuming that the wheels ll of the two wheel units shown in Fig. 1 donot slip duringtheapplication of the brakes, no further operation oftheequipment occurs except in response to varia tion of the pressure inthe control pipe i5 under Obviously, the operator may graduate theapplication on or effect a graduated release of the brakes by simplyincreasing the pressure in the control pipe in steps or decreasing thepressure. in thecontrol pipe in steps. It will be apparent that therelay valve device 27 automatically variesthe pressure in the brakecylinders l3. and consequently the degree of application of the brakesin accordancewith each variation of. the pressurein. the control pipel5..

When the car or train comes to a stop the brakes remain applied untilsuch time as the operator desires to again. start the car. The operatormay then release the brakes. by simply restoring. the brake valvehandle. 22 to its brake release position. The pressure in the controlpipe i5is correspondingly reduced touatmospheric pressure by ventingfluid under pressure through exhaust port 24 of the brake. valve. 2-],and the relay valve device 21 operates in response to the reduction ofthe pressure in the control pipe IE to atmospheric pressure to eifectthe complete venting of fluid under pressure from the brake cylinders l3and the consequent release of the brakes.

Let it nowbe assumed that when an application of the brakes is initiatedin the manner previously described, or at any time during a brakeapplication and while the car or train is being brought to a stop, theWheels of either of the wheel units shown in Fig. l begin to slip, forexample the Wheels of the left-hand wheel unit. In such case, therotative shift of the axle of that wheel unit backwardly with respect tothe disk of the corresponding wheel-slip detecting device 45 causes thecontact finger 12 to engage its associated contact 15, resultingin theestablishmentof a circuitfor energizing the winding (1 of the relay 41.This circuit extends from the positive terminal of the battery by way ofthe positive battery wire 96, branch wire 91, brush device BIa to thecontact member 13 as previously described, thence by way of the contact15, contact finger 12, connector 82, collector ring 62, brush device62a, a wire I91 including the winding a of the relay 41, negativebattery wire 99 including the contacts of the pressure switch 34 to thenegative terminal of the battery 95.

Upon the energization of the winding a of the relay 41 in the mannerjust described, the contacts and d of the relay are actuated to theirpicked-up or closed positions. The contact c is a self-holding contactand is effective to establish a holding circuit for maintaining thewinding a of the relay 41 energized independently of the contact finger12 and its associated contact 15 of the wheel-slip detecting device 45associated with the slipping wheel unit. This holding circuit extendsfrom the positive terminal of the battery 95 by way of the positivebattery Wire 96, branch wire I04, wire I05, contact 0 of relay 41, wireI01 including the winding a of relay 41, and negative battery wire 99including the contacts of the pressure switch 34 to the negativeterminal of the bat tery 95.

Bearing in mind that the relay 46 is being maintained picked-up by aholding circuit including the self-holding contact 0 thereof, it will beseen that the actuation of the contact d of relay 41 to its picked-up orclosed position establishes a circuit for energizing the magnet winding42 of the magnet valve device 28. This circuit extends from the positiveterminal of the battery 95 by way of the positive battery wire 96, abranch wire I09, magnet winding 42 of the magnet valve device 28, a wireIII including the contact 01 of relay 41 and the contact d of relay 46in series relation therein, and wire 99 directly to the negativeterminal of the battery 95. Thus, as long as the contacts of both relays46 and 41 are simultaneously actuated to their picked-up positions, themagnet winding 42 of the magnet valve device 28 is energized.

Upon energization of the magnet winding 42 of the magnet valve device28, communication from control pipe I5 through the branch pipe 29 to thecontrol chamber of the relay valve device 21 is-closed due to theshifting of the double beat valve 39 to its lower seated position and,at the same time, the section of the pipe connected directly to therelay valve device 21 is vented to atmosphere through the exhaust port44 of the magnet valve device 28. The relay valve device 21 isaccordingly operated in response to the rapid reduction of the pressurein the control chamber thereof to vent fluid under pressure at acorresponding rate from the brake cylinders I3 through an exhaust port(not visible) at the relay valve device 21.

The wheels II of the slipping wheel unit cease to decelerate because ofthe instantaneous and rapid reduction in the degree of application ofthe brakes on the wheel unit and begin to accelerate back toward a speedcorresponding to car speed. The total time elapsing between the instantthat the Wheels begin to slip and the instant they return fully to aspeed corresponding to a car speed will vary depending upon the rapidityof response of the brakes to the reduction of the pressure in the brakecylinders I3. In the majority of instances, it has been found that theslipping wheels are restored fully to a speed corresponding to car speedprior to the time that the pressure in the brake cylinders is reduced toa low pressure, such as five pounds per square inch, sufiicient to causerestoration of the movable contact 36 of the pressure switch 34 to itsopen position.

It will be apparent, therefore, that When the slipping wheels cease todecelerate and begin to accelerate back toward a speed corresponding tocar speed, the pin 69 secured to the axle I2 returns to the right-handextremity of slot 68 in the disk 65 and again bends the contact fingerII into engagement with the contact 14 and incidentally causesdisengagement of the contact finger 12 from its associated contact 15.However, in View of the holding circuit established by the self-holdingcontacts 0 of the two relays 46 and 41 and the contacts of the pressureswitch 34, such operation of the contact fingers 12 and II is withoutimmediate effect.

As long as the pressure in the brake cylinders I3 remains above fivepounds per square inch, the pressure switch 34 continues to maintain theholding circuits for the winding a of the relays 45 and 41. Accordinglythe reduction of the pressure in the brake cylinders I3 to below fivepounds per square inch is positively assured. This feature of theequipment shown whereby the reduction in the pressure in the brakecylinders below a certain pressure is positively assured in response tothe initiation of wheel slipping is, broadly, not my invention.

When the pressure in the brake cylinders I3 is reduced below five poundsper square inch, the movable contact 36 of the pressure switch 34 isrestored to its open position interrupting the holding circuit for thewinding a of each of the relays 46 and 41.

Upon the deenergization of the winding a thereof, the relay 41 isrestored to its dropped-out position. The restoration of the contact (1of relay 41 to its open position interrupts the circuit, previouslytraced, for energizing the magnet winding 42 of the magnet valve device28. The valve 39 of the magnet valve device 28 is thus instantlyrestored to its upper seated position in which it closes the exhaustcommunication for the control chamber of the relay Valve device 21 andrestores the supply communication thereto through the branch pipe 29from the control pipe I5.

The volume of the pipe 29 and the control chamber of the relay valvedevice 21 is relatively small but the resupply of fluid under pressureto the control chamber tends to cause a reduction of the pressure in thecontrol pipe l5. Due to the pressure-maintaining feature of the brakevalve 2I, fiuid under pressure sufficient to maintain a pressure in thecontrol pipe corresponding to the position of the brake valve handle 22is supplied to the control pipe automatically. Thus, upon thedeenergization of the magnet winding 42 of the magnet valve 28, thecontrol chamber of the relay valve device 21 is again charged with fluidat a pressure corresponding to that in the control pipe I5 which in turncorresponds to the position of the brake valve handle 22. The relayvalve device 21 again operates in response to the increase of pressurein the control chamber thereof to resupply fluid under pressure from thesupply pipe I4 to the brake cylinders I3 to cause reapplication of thebrakes on the wheel truck having the slipping wheels.

The relay 46 does not drop-out in response to the opening of thepressure switch 34 for the reason that, as previously pointed out, thecontact finger ll of the wheel-slip detecting device 45 of the slippingwheel unit has previously been restored into engagement with itsassociated con- .tact 14 when the slipping wheels began to accelerateback toward a speed corresponding to car speed. Thus, although theholding circuit for relay 46, including its own self-holding contact cand the pressure switch 34, is interrupted, the previously describedcircuit for initially energizing the winding (1. of the relay 46 by wayof the contact finger II and its associated contact 14 of the wheel-slipdetecting device 45 is maintained. The relay 46 does not drop-out,therefore, in response to the opening of the pressure switch 34.

When fluid under pressure is resupplied to the brake cylinders I3 inresponse to the deenergization of the magnet winding 42 of the magnetvalve 28 following restoration of the slipping wheels to a speedcorresponding to car speed, the movable contact 36 of pressure switch 34is again restored to its closed position due to the increase of thepressure in the brake cylinders to above five pounds per square inch.The previously described holding circuit for the winding a of the relay46, including the self-holding contact 0, is thereby again established.

If the wheels again begin to slip upon restoration of the brakeapplication, relay 41. is again picked-up and the magnet winding 42 ofthe magnet valve device 28 thereby again energized to efiect theinstantaneous and rapid reduction of the pressure in the brakecylinders, after which fluid under pressure is again restored to thebrake cylinders following the return of the slipping wheels to a speedcorresponding to car speed. It may thus happen that one or more cyclesof automatic brake release and brake reapplication may occur during anapplication of the brakes in bringing the car or train to a stop,depending upon the number of times the associated wheels begin to slip.At no time, however, are any of the wheels permitted to decelerate to alocked condition and slide.

In the previously described operation, slipping of the wheels I i of theleft-hand wheel unit was assumed. In the event that slipping of thewheels ll of the right-hand wheel unit occurs, the same operationresults, that is, relay 4'5 is picked-up to cause energization of themagnet winding 42 of the magnet valve 28'. The only difference in theoperation is that the initial pick-up of relay 4'! is eifected inresponse to the energization of lower winding b thereof instead of byenergization of upper winding a. The circuit for energizing winding 1)extends from the positive terminal of the battery 35 by way of thepositive battery Wire 66, branch wire Hill, brush device Sla of thewheel-slip detecting device 45 associated with the right-hand wheel unitof Fig. l, thence by way of collector ring 63 to the contact member 73on the disk 65 as previously described, contact 15, contact finger l2,brush device 62a, a wire IE2 including the winding b of relay 4?, andwire 99 including the contacts of pressure switch 34 to the negativeterminal of the battery 95. Once the relay 4? is picked-up in responseto the energization of the winding b thereof, the self-holding contactof this relay establishes the previously described holding circuit forenergizing the winding a of the relay.

In the event that the wheels of both wheel units of a wheel truck slipsimultaneously, the relay 4'5 is initially picked-up in response to theiii simultaneous energization of both its windings a and b, the windinga being maintained energized thereafter by the holding circuit,previously described, including the self-holding contact c of the relay.

In the above described operation of the brakes under the control of thewheel-slip detecting devices it was assumed that the car was travelingin a forward direction corresponding to the clockwise direction ofrotation of the axle and of the disk as seen in Fig. 3.

If the car is traveling in a reverse direction so that the axle I2 anddisk 65 in Fig. 3 rotate in a counterclockwise direction, the sequenceof operation of the contact fingers H and I2 is reversed, that is, thecontact finger 12 is normally shifted into contact with its associatedcontact due to the fact that the pin 69 in the axle l2 shifts to" theleft-hand extremity of slot 68 in disk 65 in order to drive the disk 65.

It will be apparent upon analysis that the relay 4'! is thus normallypicked-up and stuck-upby the holding circuit including the self-holdingcontact 0 thereof and that the relay 46 is picked-up only in response tothe slipping of the wheels and the consequent momentary engagement ofthe contact finger H with its associated contacts l4 due to the movementof pin 69 in the slot '68 of disk to its right-hand extremity.

It should be thus understood without further description that theequipment operates to cause, automatic reduction of the pressure in thebrake cylinders and restoration of the pressure therein no matter inwhich direction the wheels happen to be rotating at the time slippingoccurs.

When the car or train comes to a complete stop in response to theapplication of the brakes durin which slipping of the wheels occurs, thefluid pressure is always restored to the brake cylinders to a degreecorresponding to the position ofthe pressure established in the controlpipe l5 for the reason that one or the other of the relays 46 or 4'! isalways restored to its dropped-out position following the opening of thepressure switch 34 in response to the automatic reduction of thepressure in the brake cylinders l3.

With the car ortrain in a stopped position, the tension in one or theother of the contact fingers H is eifective to cause shifting of thedisk 65 with respect to the axle l2 with which it is associated in amanner to eflect separation. of both contact fingers H and F2 from theirassociated contacts 74 and E5. not result in the drop-out of both of therelays 46 and 4"! because of the holding circuit which is maintained forone or the other of the relays as long as pressure remains in the brakecylinders l3 sufiicient to maintain the pressure switch 34 closed.

When the operator of the train desires to again proceed after bringingthe car to a stop, he first releases the brakes by restoring the brakevalve handle 22 to its brake release position to effect the completeventing of fluid under pressure from the brake cylinders l3 and theconsequent release of the brakes. In such case, the movable contact 36of the pressure switch 34 is restored to its open position and therebyinterrupts the holding circuit maintained for either of the relays 46and 41. It will thus be seen that, normally, when the car or train istraveling under power with the brakes released, both the relays 46 and41 are dropped-out. Thus no energy is taken from the battery by therelays.46.

Such fact, however, does and 41 except during the application of thebrakes.

Adaptation of equipment to a train of cars As previously stated, theequipment shown in Fig. 1 controls the brakes associated with the wheelsof a single wheel truck. It will be apparent, however, that in the caseof a train of cars, the equipment shown in Fig. 1 may be duplicated foreach wheel truck. Thus the brakes throughout the train may be operatedunder the control of the operator in the same manner as described forthe single wheel truck. At the same time, the wheel-slip detectingequipment associated with each wheel truck operates as an individualunit to automatically control the brakes associated with the wheels ofthe corresponding truck and does not affect the brakes associated withother wheel trucks. Thus, when slipping of the wheels on a particularwheel truck occurs, only the brakes associated with that particularwheel truck are automatically released, the brakes associated with thewheels of other wheel trucks not having slipping wheels not beingafiected.

Summary Summarizing, it will be seen that I have disclosed a noveldevice for registering the rate of change of speed of a rotary elementand adapted to detect the slipping of vehicle wheels. The device is alsoinherently adapted to detect the direction of rotation of the rotaryelement. It will also be seen that I have provided, in association withthe wheel-slip detecting device, control apparatus whereby to effect theinstantaneous and rapid reduction in the degree of application of thebrakes associated with a vehicle wheel when the wheel begins to slip,such apparatus being effective automatically for either direction ofrotation of the vehicle wheels.

While I have shown and described a specific embodiment of my invention,various omissions, additions, or modifications will suggest themselvesto those skilled in the art, without involving a departure from thespirit of my invention. It is accordingly not my intention to limit thescope of my invention except in accordance with the terms of theappended claims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. Control apparatus for the brakes associated with the wheels of avehicle, of the type including means under the control of the operatorfor efiecting application and release of the brakes, comprising incombination, a pair of electrical relays, means associated with a wheelof the vehicle and effective during a brake application to causecontinued pick-up of only a certain one of said relays as long as theWheel does not slip and. pick-up of both of said relays only in responseto a slipping condition of the wheel, and means controlled jointly bysaid pair of relays and efiective to cause a continued reduction in thedegree of application of the brakes independently of the operator of theVehicle so long as both of said relays are picked-up simultaneously.

2. In a vehicle brake system of the type having means under the controlof the operator for effecting application and release of the brakesassociated with the wheels of the vehicle, the combination of a pair ofelectrical relays, means responsive to the direction of rotation of awheel of the vehicle and effective during a brake application forcausingpick-upof the one or the other of said relays depending upon thedirection of rotation of the wheel, means responsive to the slipping ofthe wheel due to application of the brakes for effecting pick-up of thenormally non-picked-up relay, and means controlled jointly by said pairof relays and eifective only when both relays are simultaneouslypicked-up for effecting a reduction in the degree of application of thebrakes associated with the wheel independently of the operator.

3. In a fluid pressure brake system for the wheels of a vehicle, of thetype having a brake cylinder to which fluid under pressure is suppliedto effect application of the brakes and from which fluid under pressureis released to effect release of the brakes and means under the controlof the operator for causing fluid under pres-' sure to be supplied toand released from said brake cylinder, the combination of a pair ofelectrical relays, means responsive to the rotative condition of a wheelof the vehicle for causing only a certain one of said relays to becontinuously picked-up during a brake application as long as the wheeldoes not slip and efiective to cause both of said relays to besimultaneously picked-up during a brake application whenever the wheelslips, and means controlled jointly by said pair of relays and eifectivewhen both said relays are simultaneously picked-up for causing fluidunder pressure to be released from the brake cylinder to effect areduction in the degree of application of the brakes associated with theslipping wheel, independently of the operator of the vehicle, to preventsliding of the wheel.

4. In a vehicle brake system of the type having means under the controlof the operator for effecting application and release of the brakesassociated with the wheels of the vehicle, the combination of a pair ofelectrical relays, a rotary member, means providing a driving connectionbetween a wheel of the vehicle and said rotary member and adapted topermit a limited degree of rotative movement of the rotary member withrespect to the wheel, braking means for constantly exerting a brakingeffect on the rotary member to cause said rotary member to shift to oneextremity of movement thereof with respect to said wheel when the wheeldrives the rotary member and effective to cause rotative deceleration ofthe rotary member at least at a certain rate whereby, when the wheelrotatively decelerates at a rate in excess of the rate of decelerationof the rotary member, the rotary member shifts rotatively to theopposite extremity of movement thereof with respect to the rotaryelement, means effective when the rotary member is in its one extremityof movement with respect to the said wheel to cause pick-up of one ofsaid relays, means for maintaining said relay picked-up independently ofthe last said means as long as the application of the brakes exceeds acertain degree, means effective when the rotary member is in itsopposite extremity of movement with respect to the wheel for causing theother of said relays to be picked-up, means for maintaining said otherrelay picked-up thereafter independently of the position of the rotarymember with respect to said Wheel as long as the application of thebrakes exceeds a certain degree, and means controlled jointly by saidrelays and efiective only while both of said relays are simultaneouslypicked-up for effecting a continued reduction in the degree ofapplication of the brakes associated with the said wheel.

5.,In afluid pressure operated brake system for thewheels vofasvehicle,of the type having a brake cylinder to which fluid under pressure issupplied and from which fluid under pressure is released 1 under thecontrol of the operator for effecting application and releaserespectively of the brakeszassociated with one or more wheels of thevehicle, the combination of a pair of electrical relays each of whichhas an operating wind ing effective upon energization to cause pick-upof the relays, a pressure-operated switch device operated from an opento a closed position whenever the pressure in the brake cylinder exceedsa certain pressure and restored toits open position whenever thepressure in the brake cylinder reducesbelow said certain pressure, meansresponsive to the rotative condition of a wheel of the vehicle andincluding two switches oneof which is closed as long as the wheelrotates and does not slip and the other of which is closed only whilethe wheel rotatively decelerates at a slipping rate, saidpressure-operated switch device and said on switch of thewheel-conditionresponsive means being jointly effective to causeenergization of the operating winding of one of said relays during abrake application, means effective upon energization of the operatingwinding of the said one relay for thereafter maintaining said onewinding energized independently of the said one switch of thewheel-condition-responsive means as long as the pressure-operated switchremains in its closed position, said second switch of thewheel-condition-respnsive means and said pressure-operated switch beingjointly effective to cause energization of the operating winding of thesaid second relay during a brake application, means for maintaining theoperating winding af said second relay energized independently of saidsecond switch of the wheelcondition-responsive means as long as the saidpressure-operated switch is in its closed position, and means controlledjointly by said pair of relays and efiective as long as both of saidrelays are picked-up to cause fluid under pressure to be vented from thebrake cylinder to effect a continued reduction in the degree ofapplication of the brakes associated with the slipping wheel, saidpressure operated switch being effective when the pressure in the brakecylinder reduces below said certain pressure in response to theoperation of the last said means to effect deenergization of theoperating winding of said second relay whereby the last said means isrestored to its condition for causing fluid under pressure to beresupplied to the brake cylinders.

6. In a vehicle brake system, of the type having means under the controlof the operator for effecting application and release of the brakesassociated with the wheels of the vehicle, the combination of a pair ofelectrical relays, means responsive to the rotative condition of a wheelof the vehicle and effective during a brake application for selectivelycausing continuous pickup of only the one or only the other of saidrelays depending upon the direction of rotation of the wheel as long asthe wheel does not slip and effective whenever the wheel decelerates ata slipping rate for effecting simultaneous pick-up of both of saidrelays, means controlled jointly by said pair of relays and effectiveonly while both of said relays are simultaneously pickedup to cause acontinued reduction in the degree of application of the brakesassociated with the slipping wheel, and means including means responsiveto the degree of application of the brakes for causing both of saidrelays to remain picked-up independently of thewheel-conditionresponsive means as long as the brake application exceedsa certain degree and efiective when the brake application is reducedbelow said certain degree in response to the operation of the last saidmeans for effecting drop-out of the one or thesother of said relayswhereby the last said means is restored to the condition for causingreapplication of the brakes on the slipping wheel.

7. In a vehicle brake control system, of the type having means under thecontrol of the operator of the vehicle for effecting application andrelease. of the brakes associated with the wheels of the vehicle, thecombination of a plurality of devices each of which is associatedrespectively with a corresponding vehicle wheel for detecting a slippingcondition thereof, a pair of electrical relays one or the other of whichis selectively picked-up and maintained picked-up during a brakeapplication depending upon the direction of rotation of the said wheels,either of said wheel-slip detecting devices being individually effectiveupon deceleration of the corresponding wheels at a slipping rate foreffecting pick-up of the normally non-picked-up relay, and meanscontrolled jointly by said pair of relays and effective only when bothrelays are simultaneously picked-up for effecting a reduction in thedegree of application of the brakes independently of the operator.

8. In a vehicle fluid pressure brake system, of the type having a brakecylinder to which fluid under pressure is supplied and from which fluidunder pressure is released under control of the operator for effectingapplication and release respectively of the brakes associated with aplunality of separately rotating wheels of the vehicle, the combinationof a pair of electrical relays each of which has two separate operatingWindings individually effective upon energization to cause pick-up ofthe relays, a pressure-operated switch device responsive to variation ofthe pressure in the brake cylinder "from one to the other side of :acertain pressure, a plurality of devices associated respectively withwheels corresponding thereto for detecting a slipping condition thereof,one of said wheel-slip-detecting devices being eifective jointly withthe pressure-responsive switch device to cause energization of one ofthe operating windings of one or the other of said two relays dependingupon the direction of rotation of the wheel associated therewith,another of said wheel-slip-responsive devices being effective jointlywith the pressure-operated switch device to effect energization of theother operating winding of the one or the other of said two relaysdepending upon the direction of rotation of the corresponding wheel,means effective jointly with said pressure-responsive switch device inresponse to energization of either of the windings of either of therelays for thereafter maintaining one of said windings energized as longas the pressure in the brake cylinder exceeds a certain pressure, eachof said wheel-slip-detecting devices being effective upon slipping ofthe corresponding wheel to cause energization of the correspondingwinding of one of said relays not normally energized during a brakeapplication, and means controlled jointly by said two relays effectiveto cause a continued reduction of the pressure in the brake cylinder aslong as said relays are simultaneously pickedup.

9. In control apparatus for the brakes associated with the wheels of avehicle, which control apparatus is of the type having means under thecontrol of the operator for effecting application and release of thebrakes, the combination .comprising a pair of current-responsivedevices, means effective during a brak application and in response torotation of a wheel unit of the vehicle for causing energization of onlyone of said current-responsive devices, means responsive to the slippingof the wheel unit due to application of the brakes for effectingenergization of the other of said current-responsive devices, saidcurrent-responsive devices being jointly effective only whensimultaneously energized to effect a reduction in the degree ofapplication of the brakes associated with the wheel independently of theoperator.

10. In a vehicle brake system of the type having means under the controlof the operator for effecting application and release of the brakesassociated with the wheels of the vehicle, the comloination comprising.a pair oi electrical relays, a first switch device, a second switchdevice, means responsive to rotation of a wheel unit of the vehicle foreffecting continuous closure of the said first switch device as long asthe wheel unit does not slip, means responsive to the slipping of thewheel unit for effecting closure of the said second switch device onlywhen said Wheel unit slips, said first switch device being effectivewhen closed during a brake application to cause pickup of one of saidrelays, said second switch device being effective when closed during abrake application to effect pick-up of the other of said relays, meansfor maintaining said relays pickedup once they are picked-up as long asthe brake application exceeds a certain degree, and means controlledjointly .by said pair of relays and effective only while both of saidrelays are simultaneously picked-up for effecting a continued reductionin the degree of application of the brakes associated with the wheelunit independently of the operator to below said certain degree.

11. In a fluid pressure brake system for vehicles of the railway 108.1type having a brake cylinder to which fluid under pressure is suppliedand from which fluid under pressure is released under the control of theoperator for efiecting application and release respectively of thebrakes associated with a wheel unit, the combination comprising a pairof electrical relays, a first switch device, a second switch device, athird switch device operated to a closed position only so long as thepressure in the brake cylinder exceeds a certain value, means responsiveto the rotation of the wheel unit for eiTecting closure of said firstswitch device as long as the wheel unit does not slip, means foreffecting closure of the said second switch device only when the wheelslips, said first switch device and said third switch device beingeffective when both are [closed to cause pick-up of one of said relays,said second switch and said third switch device being effective whenboth are closed to cause pick-up of the other of said relays, means formaintaining said relays picked-up independently of the said first orsecond switch device corresponding thereto once the relays arepicked-up, means under the joint control of said relays and effectiveonly when said relays are both simultaneously picked-up for effecting acontinued reduction of the pressure in the brake cylinder, said thirdswitch device being effective upon a reduction of pressure in the brakecylinder below said certain value for rendering the relay pick-upmaintaining means ineffective whereby to cause operation of the lastsaid means to effect the I'esupply of fluid under pressure to the brakecylinder and a consequent reapplication of the brakes.

CLAUDE M. HINES.

